Males ofDrosophila Melanogaster Research Articles

Activity-dependent visualization and control of neural circuits for courtship behavior in the fly Drosophila melanogaster

Males of Drosophila melanogaster exhibit stereotypic courtship behavior through which they assess potential mates by processing multimodal sensory information. Although previous studies revealed important neural circuits involved in this process, the full picture of circuits that participate in male courtship remains elusive. Here, we established a genetic tool to visualize or optogenetically reactivate neural circuits activated upon specific behavior, exploiting promoter activity of a neural activity-induced gene Hr38 With this approach, we visualized neural circuits activated in the male brain and the ventral nerve cord when a male interacted with a female. The labeling of neural circuits was additively dependent on inputs from antennae and foreleg tarsi. In addition, neural circuits that express the sex-determining gene fruitless or doublesex were extensively labeled by interaction with a female. Furthermore, optogenetic reactivation of the labeled neural circuits induced courtship posture. With this mapping system, we found that a fruitless-positive neural cluster aSP2 was labeled when a male interacted with a female, in addition to previously characterized neurons. Silencing of neurons including aSP2 led to frequent interruption of courtship and significant reduction of mating success rate without affecting latency to start courtship, suggesting that these neurons are required for courtship persistency important for successful copulation. Overall, these results demonstrate that activity-dependent labeling can be used as a powerful tool not only in vertebrates, but also in invertebrates, to identify neural circuits regulating innate behavior.

Prophage WO genes recapitulate and enhance Wolbachia-induced cytoplasmic incompatibility.

The genus Wolbachia is an archetype of maternally inherited intracellular bacteria that infect the germline of numerous invertebrate species worldwide. They can selfishly alter arthropod sex ratios and reproductive strategies to increase the proportion of the infected matriline in the population. The most common reproductive manipulation is cytoplasmic incompatibility (CI), which results in embryonic lethality in crosses between infected males and uninfected females. Females infected with the same Wolbachia strain rescue this lethality. Despite more than 40 years of research1 and relevance to symbiont-induced speciation2,3, as well as control of arbovirus vectors4,5,6 and agricultural pests7, the bacterial genes underlying CI remain unknown. Here, we use comparative and transgenic approaches to demonstrate that two differentially transcribed, codiverging genes in the eukaryotic association module of prophage WO8 from Wolbachia strain wMel recapitulate and enhance CI. Dual expression in transgenic, uninfected males of Drosophila melanogaster crossed to uninfected females causes embryonic lethality. Each gene additively augments embryonic lethality in infected males crossed to uninfected females. Lethality associates with embryonic defects that parallel those of wild type CI and is notably rescued by wMel-infected embryos in all cases. The discovery of cytoplasmic incompatibility factor genes cifA and cifB pioneers genetic studies of prophage WO-induced reproductive manipulations and informs Wolbachia’s ongoing utility to control dengue and Zika transmission to humans.

Male Drosophila melanogaster learn to prefer an arbitrary trait associated with female mating status.

Although males are generally less discriminating than females when it comes to choosing a mate, they still benefit from distinguishing between mates that are receptive to courtship and those that are not, in order to avoid wasting time and energy. It is known that males of Drosophila melanogaster are able to learn to associate olfactory and gustatory cues with female receptivity, but the role of more arbitrary, visual cues in mate choice learning has been overlooked to date in this species. We therefore carried out a series of experiments to determine: 1) whether males had a baseline preference for female eye color (red versus brown), 2) if males could learn to associate an eye color cue with female receptivity, and 3) whether this association disappeared when the males were unable to use this visual cue in the dark. We found that naïve males had no baseline preference for females of either eye color, but that males which were trained with sexually receptive females of a given eye color showed a preference for that color during a standard binary choice experiment. The learned cue was indeed likely to be truly visual, since the preference disappeared when the binary choice phase of the experiment was carried out in darkness.This is, to our knowledge 1) the first evidence that male D. melanogaster can use more arbitrary cues and 2) the first evidence that males use visual cues during mate choice learning. Our findings suggest that that D. melanogaster has untapped potential as a model system for mate choice learning.

The Deleterious Effects of High Inbreeding on Male Drosophila melanogaster Attractiveness are Observed Under Competitive but not Under Non-competitive Conditions

In order for the male courtship traits to honestly signal quality they need to be condition-dependent. Moreover, if these traits capture genetic variation in condition they should resemble life-history traits in being subject to strong directional selection and, consequently, suffer strong inbreeding depression. In this study we investigated the effect of high inbreeding on male attractiveness by assessing mating success, mating speed and copulation duration of inbred, outbred and crossbred (constructed by crossing separate, randomly chosen inbred lines) males of Drosophila melanogaster. When set to compete against a standardized competitor and compared to the success rate of the crossbred lines, inbreeding significantly reduced male mating success. Under competition, outbred males initiated copulation significantly sooner than crossbred and inbred males. Under non-competitive conditions, no effect of inbreeding was found on either mating speed or copulation duration. Both mating success and mating speed showed much higher inbreeding depression than male size.

Neuroprotective properties of phytochemicals against paraquat-induced oxidative stress and neurotoxicity in Drosophila melanogaster

Environmental toxicants like paraquat (PQ) induce the increase of oxidative stress, which is likely to lead to various neuropathological symptoms. Although the Drosophila system is applicable for anti-oxidative and neuroprotective drug discovery, this system remains to be more exploited in various aspects. In this study, using Drosophila as a model animal, we have examined the anti-oxidative and neuroprotective properties of plant-derived compounds against oxidative damage and neurotoxicity induced by paraquat, which is a widely used herbicide. In this study, paraquat showed LC50 at 24.7mM to adult males of Drosophila melanogaster within 24h. Dietary feeding of curcumin, quercetin, Sanguisorba officinalis, and Zedoariae rhizoma extracts prior to paraquat exposure extended lifespan and enhanced motor activities of flies. These compounds modulated the expression level of several genes associated with anti-oxidative and anti-aging effects such as sod1, sod2, cat, gstD1, and mth genes. Also, same treatments of phytochemicals to flies ameliorated other oxidative stress index factors such as ROS levels and superoxide dismutase. In contrast, no significant effects on catalase activities were observed. Additionally, the dietary feeding of phytochemical substances also reduced acetylcholine esterase activities, which were dramatically increased by paraquat treatment, implying that these phytochemicals also affected neuronal systems. Present study demonstrates that the dietary feeding of phytochemicals prior to paraquat exposure has anti-oxidative and neural protective effects, which leads to the recovery of behaviors and lifespan in fruit flies.

Molecular evidence for increased regulatory conservation during metamorphosis, and against deleterious cascading effects of hybrid breakdown in Drosophila

BackgroundSpeculation regarding the importance of changes in gene regulation in determining major phylogenetic patterns continues to accrue, despite a lack of broad-scale comparative studies examining how patterns of gene expression vary during development. Comparative transcriptional profiling of adult interspecific hybrids and their parental species has uncovered widespread divergence of the mechanisms controlling gene regulation, revealing incompatibilities that are masked in comparisons between the pure species. However, this has prompted the suggestion that misexpression in adult hybrids results from the downstream cascading effects of a subset of genes improperly regulated in early development.ResultsWe sought to determine how gene expression diverges over development, as well as test the cascade hypothesis, by profiling expression in males of Drosophila melanogaster, D. sechellia, and D. simulans, as well as the D. simulans (♀) × D. sechellia (♂) male F1 hybrids, at four different developmental time points (3rd instar larval, early pupal, late pupal, and newly-emerged adult). Contrary to the cascade model of misexpression, we find that there is considerable stage-specific autonomy of regulatory breakdown in hybrids, with the larval and adult stages showing significantly more hybrid misexpression as compared to the pupal stage. However, comparisons between pure species indicate that genes expressed during earlier stages of development tend to be more conserved in terms of their level of expression than those expressed during later stages, suggesting that while Von Baer's famous law applies at both the level of nucleotide sequence and expression, it may not apply necessarily to the underlying overall regulatory network, which appears to diverge over the course of ontogeny and which can only be ascertained by combining divergent genomes in species hybrids.ConclusionOur results suggest that complex integration of regulatory circuits during morphogenesis may lead to it being more refractory to divergence of underlying gene regulatory mechanisms - more than that suggested by the conservation of gene expression levels between species during earlier stages. This provides support for a 'developmental hourglass' model of divergence of gene expression in Drosophila resulting in a highly conserved pupal stage.

Induction of mutations which shorten the adult life span in Drosophila melanogaster

Koivisto, K. and Portin, P. 1987. Induction of mutations which shorten the adult life span in Drosophila melanogaster.- Hereditas 106: 83–87. Lund, Sweden. ISSN 0018–0661. Received April 10, 1986 Yellow (y, 1 - 0.0) males of Drosophila melanogaster were treated with ethylmethane sulphonate (EMS). The males were crossed with Muller-5 (Basc) females. Of the 252 chromosomes tested 127 (50.4%) contained a lethal mutation, but we were also able to extract 51 homozygous yellow stocks which contained a EMS-treated X chromosome. 13 of the stocks (25.5 %) contained a mortality mutation (mor (1)), i.e., the duration of adult life in these stocks was considerably decreased as indicated by the mean length of life and survival curves. Furthermore, in one stock the adult life span was significantly increased. In each case of the mortality mutations the mean life span and the survival curve were different, indicating different action of the mutations. However, it was possible to group the mortality mutations into three major classes each characterized by similar typical survival curves. The different action of the mortality mutations, however, suggests that they are mutations of different genes. Therefore, and on the basis of the frequency of mortality mutations it is concluded that many genes can mutate to mortality mutations, tentatively suggesting that there are many genes which affect ageing in a non-specific way.

Fly Sexual Dimorphism

In a comparative microarray analysis, Ranz et al. have discovered that sex determines how genes are expressed in two closely related species of fruit fly. For example, males of Drosophila melanogaster have up-regulated olfactory functions, whereas males of D. simulans have up-regulated visual functions, hinting at the evolution of differences in mating behavior. Furthermore, male-biased and female-biased genes have specific chromosomal locations, which suggests that gene location may be functionally more important than expected.J. M. Ranz, C. I. Castillo-Davis, C. D. Meiklejohn, D. L. Hartl, Sex-dependent gene expression and evolution of the Drosophila transcriptome. Science 300, 1742-1745 (2003). [Abstract] [Full Text]

Diurnal Rhythm of Protein Carbonyl as an Indicator of Oxidative Damage in Drosophila melanogaster: Influence of Clock Gene Alleles and Deficiencies in the Formation of Free-Radical Scavengers

In males of Drosophila melanogaster, protein carbonyl was determined as an indicator of damage by free radicals; this parameter was chosen because it is not affected by self-sustaining progression of radical reaction chains, in contrast to indicators based on lipid peroxidation. The diurnal time patterns were determined in wild-type flies, strain Canton S, and the following mutants, on a Canton S genetic background: the short-period mutant per s; the arrhythmic mutant per 0, which is, at the same time, deficient for melatonin formation, due to its inability to express hydroxyindole O-methyltransferase; the mutant rosy (ry 506), which is hypersensitive to oxidants because of its deficiency in the formation of the physiological free-radical scavenger urate. Wild-type flies exhibit a protein carbonyl rhythm of only moderate amplitude; an increase of protein damage is only found in the mid-scotophase. In per s, the nocturnal protein carbonyl maximum of flies kept in LD 12:12 is markedly elevated; additionally, a secondary maximum appears in the middle of photophase. The arrhythmic mutant per 0 does not exhibit diurnal fluctuations, even not in LD. Highest concentrations of protein carbonyl are found in the urate-null mutant ry. Its temporal pattern largely deviates from the those of the other strains by showing highest rates of damage in the morning and during the day.

Molecular and genetic dissection of a reproductive isolation gene, zygotic hybrid rescue, of Drosophila melanogaster.

Hybrids from the cross between males of Drosophila melanogaster and females of its sibling species (D. simulans, D. mauritiana, or D. sechellia) are embryonic lethal when they carry the wild type allele of zygotic hybrid rescue (zhr) from D. melanogaster. The zhr gene has been mapped in the proximal region of the X heterochromatin slightly distal to the proximal breakpoint of In(1)sc8, the region rich in 1.688 g/cm3 satellite DNA. Since this satellite DNA does not exist in the sibling species, the satellite DNA was considered to be involved in the hybrid lethality. We examined the hypothesis molecular cytogenetically. The results are (1) three Df(1)zhr chromosomes carried this satellite DNA, and (2) hybrids were viable even if the amount of the satellite DNA in hybrids was increased by adding minichromosomes Dp(1;f)1205 and Dp(1;f)1187 into the genome. These results do not support the above hypothesis.

Studies on mutagen sensitive strains of Drosophila melanogaster. XI. Survival (dominant lethality) after X-irradiation and relation to recessive lethals and translocations

Muller-5 males of Drosophila melanogaster were irradiated in N 2 or O 2 and mated to excision repair deficient, post-replication repair deficient ( mei-9 a, mei-41 D5, mus101 D1, mus201 D1, mus302 D1, mus306 D1 and mus308 D2 ) or repair proficient females. The surviving fraction (dominant lethality) was estimated in the F 1 and used to reassess existing recessive lethal and translocation data. The surviving fraction was found to decrease if repair deficient females were used (maternal effect). The dose-effect curves are often biphasic with a steeper slope at low doses than at high ( ≧5 Gy ) doses of X-rays. The high dose part of the curve is sensitive to oxygenation during irradiation and is affected significantly by the mutants with low fertility ( mei-9, mus101 and mus302). The low dose component is not sensitive to oxygenation during irradiation and seems influenced by all seven repair deficient mutants. The sensitivity of the high dose part to oxygenation suggests that this part is related mainly to DNA break damage, while in the low dose part base damage seems more important. Existing recessive lethal and translocation data were plotted against the surviving fraction for a reassessment. In excision repair deficient mutants translocation induction is lower compared to repair proficient flies at the same level of survival (i.e., dominant lethality). Likewise in post-replication repair deficient mutants induction of recessive lethals is decreased. However the frequency of respectively induced recessive lethals and translocations obtained at the same level of X-rays was the same in repair deficient and proficient backgrounds. It is concluded that genetic damage recovered in a repair deficient background is likely to be qualitatively different even if the frequency of the damage induced by a given dose is not altered.

A selective method for studying primary sex chromosome non-disjunction in females and males and X-Y exchange in males of Drosophila melanogaster including a demonstration of euchromatic X-Y exchange.

A selective method was developed, based on negative complementation of the Abruptex alleles of the Notch locus, for studying primary sex chromosome non-disjunction in females and males of Drosophila melanogaster and X-Y exchange in males. The results show that the frequency of primary non-disjunction of structurally normal X chromosomes was lower than the frequency of X-derY non-disjunction in males. Double exchange between the X and the derY chromosome in the male occurs with a frequency of at least 0.091%. Single exchanges are naturally expected to occur with even higher frequency. Exchanges were interestingly at least partly of euchromatic nature. The origin of these exchanges is at least partly of gonial origin.

Habituation of the Proboscis Extension Response as a Function of Age in <i>Drosophila melanogaste</i><i>r</i>

Habituation of the proboscis extension response induced by sugar tarsal stimulation was individually studied in males of Drosophila melanogaster all along the adult life span (2-71 days of age at 25 degrees C). A polynomial regression fits the best the results: the speed of acquisition of this kind of learning decreases between the ages of 3 and 35 days, a plateau being observed in flies older than 35 days. Similar results have been previously obtained using associative learning tasks of increasing complexity. These effects of age could be due to a memory impairment, but also to deficits in the process of central inhibition of irrelevant motor responses.

Detection of chromosomal aberrations in the progenies of hydroxylammonium sulphate-induced recombinants in males ofDrosophila melanogaster

Chromosomal aberrations were detected in the progenies of hydroxylammonium sulphate-induced recombinants ofaristaless-dumpy anddumpy-black regions of the males ofDrosophila melanogaster. When males from homozygous lines derived from these male recombinants were crossed to females from an aberration-free stock, the chromosomal aberrations were not recovered in recombinant heterozygotes. Implications of these observations are discussed in relation to role of chromosomal aberrations in induced male recombination inD. melanogaster.

Clusters of premeiotic ring-X chromosome loss are not observed in males of Drosophila melanogaster

Clusters of premeiotic ring-X chromosome loss are not observed in males of Drosophila melanogaster

Induction and genotypic verification of recombinants in males ofDrosophila melanogaster

Ethyl methanesulphonate (0·75%) was mixed with food (1∶9) and fed to developing F1 (Oregon-K+/dumpy black cinnabar, dp b cn) individuals in second one-third part (54–86 h after egg deposition) of larval life, at 25±1°C, for inducing recombination in males ofDrosophila melanogaster. In control and 0·75% ethyl methanesulphonate experiments, pooled test cross progeny comprised 3475 and 13887 flies, respectively, out of which 9 and 236 were recombinants. From these, 9 and 192 recombinants were further test-crossed and 55·5% and 87·0% were verified, respectively. Non-reciprocal recombination was observed indp-b but not inb-cn region with 0·75% ethyl methanesulphonate as evidenced by high frequency of +b cn male recombinants over its complementary classdp ++. Majority of the +b cn male recombinants verified did not produce in their test cross progeny the two phenotypes (+b cn anddp b cn) in expected 1∶1 ratio contrary to +b cn female recombinants, suggesting influence of cytoplasm in transmission of recombinant (+b cn) phenotype from male.

Transmission of male recombination, segregation distortion and sex-ratio imbalance inDrosophila melanogaster

From the first test cross progenies of control (no larval transfers; no ethyl methanesulphonate), physical stress (two larval transfers; no ethyl methanesulphonate) and 0.75% ethyl methanesulphonate (two larval transfers; 0.75% ethyl methanesulphonate)-treated F1 (Oregon K +/dumpy black cinnabar, dp b cn) males ofDrosophila melanogaster, respectively, 6,10 and 52 wild-looking first test cross males were again test crossed to obtain second generation. The overall percentages of male recombination detected in the second test cross progenies, in the three sets of experiments, were statistically the same as those in the first test cross progenies. Thus the enhanced male recombination caused by physical stress (with or without ethyl methanesulphonate) was transmitted to next generation. Non-reciprocal male recombination was observed indp b but not inb cn region in both first and second test cross progenies. Three abnormalities, (i) production of wild-type flies in majority overdp b cn type, (ii) Non-Mendelian segregation atdp b andcn loci and (iii) sex-ratio differences fordp bcn and +b cn types observed in test cross progenies of F1 males ofDrosophila melanogaster were transmitted to next generation when induced with 0.75 % ethyl methanesulphonate but not when these abnormalities were induced with physical stress. The data suggest possible association of non-reciprocal male recombination, segregation distortion and sex-ratio imbalance inDrosophila melanogaster. In fact these may be representing different aspects of the same phenomenon

The in vitro synthesis kinetics of proteins and RNA in accessory sex glands of mated and unmated males ofDrosophila melanogaster

Summary In the accessory sex glands of mated and unmated males of Drosophila melanogaster, the rate of protein synthesis, studied in vitro, was higher in mated than in unmated males. The curves consisted of successive peaks, the first of which was reached at between 15 and 30 min and the second at 6 h. RNA synthesis correlated with that of proteins in both mated and unmated males. Both protein and RNA synthesis appeared discontinuous. The DNA did not replicate in the nucleus of secretory cells of unmated male accessory glands during the 24 h of observation. The decreases recorded in the kinetics curves were consistent with a release of labeled proteins into the incubation medium, but the pulse-chase labeling technique showed that the drops in the curves also correlated with a strong decrease in protein synthesis more marked in mated than in unmated males. In the successive peaks specific proteins seemed to be synthesized though a strict time scale was adhered to with respect to multimated males.

A further characterization of Drosophila cuticular monoenes using a mass spectrometry method to localize double bonds in complex mixtures

Positions of double bonds of olefins of complex mixtures, such as those of Drosophila cuticular hydrocarbons, have been determined using a simple method combining methoxymercuration-demercuration of extracts and analysis by gas chromatography-mass spectrometry using ammonia for chemical ionization. Chemical similarities between cuticular monoenes of both sexes of Drosophila simulans and males of Drosophila melanogaster are specified: the major isomer is always in position 7.

Linear relationship between lethal mutation yield and intake of ethyl methanesulfonate in Drosophila melanogaster.

Males of Drosophila melanogaster were fed sucrose solutions containing various concentrations of EMS (from 0.25 to 10 mM) for 24 hr. To measure the intake of an EMS solution, 3H-labeled sucrose was added to the feeding solution, and the 3H activity inside the flies was used as a measure for the intake volume of EMS solution. Each absorbed dose of EMS was estimated from the intake volume of an EMS solution multiplied by its EMS concentration in the feeding solution in a way similar to that described in a previous report [Ayaki et al, 1984]. The relationship between the estimated absorbed dose and the exposure concentration was almost linear in a low concentration range but became concave with a downward curvature in a high concentration range. The dose-response relationship between the frequency of sex-linked recessive lethals and the estimated absorbed dose showed no deviation from linearity at all the five absorbed doses tested. It may be concluded that the absorbed doses thus estimated were very close to true absorbed doses, indicating the usefulness of the present method for dosimetry of chemicals to be given to flies.